title: Patterns of isotope uptake in sequential postoperative bone scan in undisplaced femoral-neck fractures.
abstract: OBJECTIVE
  We aimed to investigate the changing pattern of isotope uptake in the sequential bone scan test for the prediction of osteonecrosis of the femoral head in patients with an undisplaced femoral-neck fracture.
  
  
  METHODS
  Fifty-four cases of sequential bone scan for nondisplaced femoral-neck fracture treated by internal fixation with cannulated screws between 2000 and 2009 were retrospectively studied. The mean follow-up period was 4.2 years. The first postoperative bone scan was performed two weeks postoperatively in all patients. Second, third, and fourth follow-up bone scans were performed at one to six months, 12-18 months, and 18-24 months postoperatively.
  
  
  RESULTS
  Mean femoral-head ratio (FHR) in the first postoperative bone scan was 0.99. Although it was under 1.0 in 38 patients (70.4 % of the 54 patients), only one patient developed osteonecrosis of the femoral head. The others showed hot uptake in their second follow-up bone scan. Mean FHRs in the second, third, and fourth postoperative bone scans were 1.69, 1.29, and 1.05, respectively, and there were significant statistical differences in each follow-up period (P = 0.035). In addition, there were unique patterns of isotope uptake with the passage of time, such as cold uptake in the early stage, hot uptake in a couple of months, and iso-uptake in the late stage.
  
  
  CONCLUSIONS
  Early postoperative bone scan results should not be over interpreted when predicting osteonecrosis of the femoral head.
authors.affiliation: Bundang Hospital, Seoul National University, Seongnam-si, South Korea.
authors.forename: Byung Ho
authors.initials: BH
authors.lastname: Yoon
authors.forename: Young Woong
authors.initials: YW
authors.lastname: Kim
authors.forename: Hyung Ku
authors.initials: HK
authors.lastname: Yoon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001863:Bone Screws; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery*; D005269:Femur / Q000000981:diagnostic imaging*; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D013667:Technetium; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D013667:Technetium